1. Field of the Invention
The present invention relates to a solid electrolytic capacitor having an anode terminal exposed from a mold resin portion coating a capacitor element and being capable of being surface-mounted, and to a manufacturing method therefor.
2. Description of Related Art
A solid electrolytic capacitor having a structure shown in FIG. 13 has been conventionally known. A capacitor element 27 included in the solid electrolytic capacitor includes an anode element 25 made of a sintered body of a valve-action metal (tantalum, niobium, titanium, aluminum, etc.), a dielectric coating 24 made by oxidizing a surface layer of the anode element, and a cathode layer 23 having sequentially formed therein a solid electrolyte layer 21 made of a conductive inorganic material such as manganese dioxide or a conductive organic material such as TCNQ complex salt, a conductive polymer, etc. and a cathode lead layer 22 made of carbon, silver, etc. An anode lead frame 52 is connected to an anode lead member 26 planted on one end surface of the anode element 25, while a cathode lead frame 42 is connected to the cathode layer 23. A periphery of the capacitor element 27 is coated and sealed by a mold resin portion 72 made of epoxy resin or the like. The anode lead frame 52 and the cathode lead frame 42 are bent along a surface of the mold resin portion 72 (see JP 10-64761 A).
However, there has been a problem that the capacitor element 27 cannot be sufficiently large in overall size relative to a solid electrolytic capacitor finished product because the solid electrolytic capacitor of the above-described structure needs to have an entire periphery of the capacitor element 27 coated with a mold resin. Accordingly, there has been proposed a technique, as shown in FIG. 14, of incorporating a capacitor element 20 with a larger occupying volume relative to an overall size of a solid electrolytic capacitor finished product by mounting the capacitor element 20 on a platy anode terminal 50 and cathode terminal 40 to make a gap as small as possible between an outer peripheral surface of the capacitor element 20 and an outer peripheral surface of a mold resin portion 70 (JP 2001-244145 A). In a solid electrolytic capacitor 10 shown in FIG. 14, an anode lead member 30 projecting from the capacitor element 20 is connected to the anode terminal 50 via a bolster member 60. In a manufacturing process for the solid electrolytic capacitor 10, as shown in FIG. 15, a terminal frame 90 is produced which is provided with an H-shaped opening 98 to have an anode terminal portion 97 and a cathode terminal portion 96. Thereafter, the bolster member 60 is placed on the anode terminal portion 97 of the terminal frame 90, and then the bolster member 60 is connected to the terminal frame 90 by resistance welding. Next, the capacitor element 20 is placed on the terminal frame 90 to connect the anode lead member 30 of the capacitor element 20 to the bolster member 60 and also to connect a cathode portion to the cathode terminal portion 96. Then, after the capacitor element 20 is coated with a mold resin, the solid electrolytic capacitor 10 shown in FIG. 14 is finished through a cutting process using a dicing saw.
In the above-described solid electrolytic capacitor, an ESR (Equivalent Series Resistance) and an ESL (Equivalent Series Inductance) in the solid electrolytic capacitor finished product can be reduced because it is unnecessary to provide a lead frame bent along a surface of an enclosure resin part as conventionally, so that a current path from the capacitor element to a circuit board can be shortened.
However, in the manufacturing process for the solid electrolytic capacitor shown in FIG. 14, it is necessary to accurately place the bolster member 60 with an extremely short length of the order of 0.7 mm on the anode terminal portion 97 of the terminal frame 90 with a width of the order of 1.4 mm as shown in FIG. 15. Therefore, especially in a manufacturing process in which many capacitor elements 20 are mounted on the terminal frame 90 having many unit terminal areas formed therein each including the anode terminal portion 97 and the cathode terminal portion 96, it is extremely difficult to position and fix bolster members 60 one by one on respective anode terminal portions 97 of the unit terminal areas. This has been causing a problem of poor productivity.